5-Amino-3-methylpyrazole is a compound well known as an intermediate used in the field of fine chemicals (e.g., photographic chemicals, medicines and agricultural chemicals). It has also been known that the compound can be produced, for example, by the following methods.
(1) A method which comprises reacting acetonitrile with metallic sodium, sodium hydride or the like to obtain diacetonitrile, and reacting diacetonitrile with hydrazine (for example, J. Heterocyclic Chem., 11, 423 (1974)).
(2) A method which comprises reacting crotononitrile with chlorine to obtain 2,3-dichlorobutyronitrile, dehydrochlorinating 2,3-dichlorobutyronitrile in the presence of a base (e.g., potassium t-butoxide) to obtain 2-chloro-2-butenonitrile, and reacting 2-chloro-2-butenonitrile with hydrazine (for example, J. Heterocyclic Chem., 19, 1267 (1982)).
(3) A method which comprises reacting sodium cyanide with propargyl chloride to form 2,3-butadienenitrile and reacting 2,3-butadienenitrile with hydrazine (for example, Ann., 624, 1 (1959)).
However, the method (1) has a problem of using such agents having the danger of spontaneous ignition as metallic sodium and sodium hydride. The method (2) has a problem that crotononitrile, a starting material, is expensive. The method (3) has a problem of using explosive propargyl chloride.